This invention relates to fuel feed systems for supplying fuel to an internal combustion engine, particularly marine engines, and, more particularly, to such fuel feed systems which include a fuel vapor separator.
Attention is directed to the fuel vapor separator illustrated in U.S. Pat. No. 1,269,787 issued June 18, 1918. Attention is also directed to the fuel feed systems illustrated in the following U.S. patents.
______________________________________ PATENTEE U.S. PAT. NO. ISSUE DATE ______________________________________ Mitterer 2,191,490 February 27, 1940 Ebel, et al. 2,323,525 July 6, 1943 Green, et al. 2,445,113 July 13, 1948 Jordan 2,969,110 January 24, 1961 Tutch 3,314,665 April 18, 1967 Brown 3,709,202 January 9, 1973 Sellman 4,129,106 December 12, 1978 Kurahashi, et al. 4,168,687 September 25, 1979 Keane 4,385,615 May 31, 1983 Haynes 4,450,820 May 29, 1984 ______________________________________
Attention is also directed to Walsworth U.S. Pat. No. 4,539,949 issued Sept. 10, 1985, which is incorporated herein by reference.
Present marine engines have the fuel feeding system of the boat located on the suction side of the engine fuel pump. The tank, fuel feeding line(s), tank switching valve(s), anti-siphon valve(s) and fuel filter(s) of a typical boat mounted fuel feeding system require the engine mounted fuel pump to draw fuel (under vacuum) through the system prior to delivery to the engine fuel system which primarily includes a carburetor and fuel pump.
Such typical marine fuel feeding systems involve a restriction to fuel flow due to the sum of the pressure-drops across the individual components of the fuel feeding system. The distribution system requires fuel pump vacuum to pull the fuel through the fuel feed system at a sufficient rate to supply the fuel demand requirements of the engine. The sum of the pressure-drops (resistance to flow) of the fuel feeding system and the vacuum required for sufficient flow leads to a tendency for the fuel to flash into a vapor, commonly referred to as vapor lock. The tendency of gasoline fuels to vaporize at low temperatures and pressures less than atmospheric is a function of the aromatic content and reid vapor pressure of the fuel. The trend of present gasolines and alcohol extended gasolines is toward a higher aromatic content and reid vapor pressure which greatly contributes to the vapor lock tendency. Vapor lock or near vapor lock can result in erratic engine operation, loss of power output, or at worst engine damage due to the leaning effect.
The current recommended practice for twin marine engine installations is to connect each engine to its own separate fuel feeding system, i.e., fuel tank withdrawal tube, anti-siphon valve, fuel feeding line and filter. This practice is recommended due to the fact that twin engines running off of one fuel feeding system results in high flow rates which, in turn, result in a greater tendency to form fuel vapor on the suction side of the engine fuel pumps.